| 英文摘要 |
Clear zonation from seaward to landward is absent in Sri Lankan mangroves. However, a patchy zonation within the mangroves can be observed. We hypothesized that this patchy distribution, in mangroves in Sri Lanka is caused by the variation in soil edaphic factors. A study was conducted on mangroves on the east coast of Sri Lanka using eighty-six 10 m´10 m quadrates placed in five selected mangroves. Mangrove species >1cm dbh were identified and recorded. Soil samples were collected from each quadrat. Soil bulk density, salinity, pH and conductivity were measured with standard protocols. Differences in bulk density, pH, salinity and conductivity among sites were determined using ANOVA. Hierarchical agglomerative clustering (HAC) and nonmetric multidimensional scaling (NMDS) were conducted to determine the plots with similar vegetation. Redundancy analysis (RDA) was used to identify the edaphic factors determining the plant assemblages. No significant differences were observed in edaphic factors among mangrove sites, except that the soil salinity of Pottuvil lagoon was significantly higher than that of other sites. HAC and NMDS both reveal six plant communities. RDA showed that salinity influenced mangrove community assemblages, although site had a stronger overall effect. The Rhizophora–Lumnitzera–Excoecaria community was associated with higher soil salinity compared to the Lumnitzera–Excoecaria and Heritiera communities. These results support the hypothesis of patchy zonation in Sri Lankan mangroves, with salinity and site-specific factors such as anthropogenic disturbance and hydrology shaping the observed community patterns. |
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